The central objective of this proposal is to provide an interface between molecular genetics and the physical chemistry of photosynthesis. This proposal outlines experiments aimed at the isolation of genes from Rhodopseudomonas capsulata coding for polypeptides in the photosynthetic apparatus (PSA). Once identified the genes coding for the reaction center (RC) and light harvesting (LH) polypeptides will be sequenced. The protein sequences inferred from the DNA sequence will be a first step in the understanding of how these polypeptides mediate the conversion of light into the chemical potentials that drive cellular metabolism. The gene organization of the PSA sequences will be basic to models explaining the induction and regulation of the PSA components.